# ========= # fmap on lists = map to list demo_list = [0, 1, 2, 3] assert fmap(f, demo_list) == [1, 2, 3, 4] # fmap on tuples = map to tuple demo_tuple = tuple(demo_list) assert fmap(f, demo_tuple) == (1, 2, 3, 4) # fmap on functions = function composition # fmap(f, g) = lambda x: f(g(x)) assert fmap(f, lambda i: i * 3)(1) == 4 # fmap on Maybe = function application on Just, Nothing on Nothing assert fmap(f, Nothing) == Nothing assert eq(fmap(f, Just(1)), Just(2)) # fmap on Tree = recursive fmap on branches, application on value in leafs # I.e., if the original is # # /\ # / 4 # /\ # 2 3 # # applying fmap f will yield # # /\ # / 5 # /\ # 3 4
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
# MA 02110-1301 USA
'''Some demonstrations of the Eq typeclass and its `eq` and `ne` functions'''
from typeclasses.eq import eq, ne
import typeclasses.instances.list
import typeclasses.instances.tuple
from typeclasses.instances.maybe import Just, Nothing
from typeclasses.instances.tree import Branch, Leaf
# List
assert eq([1, 2, 3], [1, 2, 3])
assert ne([0, 1, 2], [1, 2, 3])
# Tuple
assert eq((
1,
2,
3,
), (
1,
2,
3,
))
assert ne((
0,
1,
2,
def __str__(self):
return 'Leaf %r' % self.value
def __repr__(self):
return 'Leaf %r' % self.value
class Branch(Tree):
def __init__(self, left, right):
self.left = left
self.right = right
def __str__(self):
return 'Branch (%r) (%r)' % (self.left, self.right)
def __repr__(self):
return 'Branch (%r) (%r)' % (self.left, self.right)
instance(Functor, Tree, lambda f, o: Leaf(f(o.value)) if isinstance(o, Leaf)
else Branch(fmap(f, o.left), fmap(f, o.right)))
instance(Eq, Tree,
lambda a, b:
a.value == b.value if (
isinstance(a, Leaf) and isinstance(b, Leaf))
else (eq(a.left, b.left) and eq(a.right, b.right)) if (
isinstance(a, Branch) and isinstance(b, Branch))
else False,
None)
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
# MA 02110-1301 USA
'''Some demonstrations of the Eq typeclass and its `eq` and `ne` functions'''
from typeclasses.eq import eq, ne
import typeclasses.instances.list
import typeclasses.instances.tuple
from typeclasses.instances.maybe import Just, Nothing
from typeclasses.instances.tree import Branch, Leaf
# List
assert eq([1, 2, 3], [1, 2, 3])
assert ne([0, 1, 2], [1, 2, 3])
# Tuple
assert eq((1, 2, 3, ), (1, 2, 3, ))
assert ne((0, 1, 2, ), (1, 2, 3, ))
# Maybe
assert eq(Nothing, Nothing)
assert eq(Just(1), Just(1))
assert ne(Just(1), Just(2))
assert ne(Just(1), Nothing)
# Tree
assert eq(Branch(Branch(Leaf(0), Leaf(1)), Leaf(2)),
Branch(Branch(Leaf(0), Leaf(1)), Leaf(2)))
assert ne(Branch(Branch(Leaf(0), Leaf(1)), Leaf(2)),
Branch(Branch(Leaf(0), Leaf(1)), Branch(Leaf(2), Leaf(3))))
